My wife and I just did a short hike at Norman Bird Sanctuary this past Sunday and it was great. You park at the welcome center and then it's more like a walk to reach the different trails available. There are some portions that feel like a hike (uphill, over rocks), but it's really casual.

They will start charging $7 per adult on April 1 but before that date it is free to walk the trails. That's only a few days notice but if you have Thursday or Friday off then it's free on those days.